Color television tube structure



March 8, 1955 R. R. MACHLETT 2,703,350

7 COLOR TELEVISION TUBE STRUCTURE Filed Dec. 28, 1951 O 2 Sheets-Sheet 1 ATTORNE March 8, 1955 R. R. MACHLETT 2,703,850

COLOR TELEVISION TUBE STRUCTURE I Filed Dec. 28, 1951 2 Sheets-Sheet 2 FIG. 4

l E, III

FIG. 8

INVENTOR RAYMOND R. MACHLETT United States Patent COLOR TELEVISION TUBE STRUCTURE Raymond R. Machlett, New Canaan, C0nn., assignor to Machlett Laboratories, Incorporated, Springdale, Conn., a corporation of Connecticut Application December 28, 1951, Serial No. 263,864

1 Claim. (Cl. 313-72) This invention concerns an improved structure for use in a color television receiving tube of the type described in U. S. patent application Serial No. 249,356, the invention of Samuel T. Yanagisawa and Henry F. Miserocchi.

The structure invented by Yanagisawa and Miserocchi makes possible the use of a single-gun type cathode ray tube structure to produce color pictures. The pictures are produced by a novel screen arrangement wherein one surface of a rigid translucent plate is coated with phosphor and a plurality of phosphor coated metallic strips are arranged generally parallel to each other and generally transverse to the translucent plate so that their ends lie adjacent opposite edges of the plate. The strips are supported on members which are mounted on the plate and which extend along said opposite edges of the plate. The strips are affixed to said members at only one end, adjacent strips being afiixed at opposite ends. Thus, in order to prevent their lateral movement and consequent shorting, various spacing means have been employed to separate the strips.

Most of these spacing means have extended essentially perpendicular to the strips along their edges which are remote from the plate, several rows of spacing means usually being employed. Such spacing means may be either conductive or dielectric. The conductive means may be fixed permanently to the strips, as by Welding, but they cannot be fixed to adjacent strips and hence do not function adequately as a spacing means as between adjacent strips. Furthermore, conductive spacers tend to disrupt the electric field between plates thereby causing shadows or distortion of the picture. On the other hand, dielectric spacers, while providing satisfactory separation of adjacent strips, may not be fixed in place. Thus, they are subject to displacement or derangement by mechanical shocks of various kinds.

My invention provides a means for accurately spacing the metallic strips without separating the strips by means which are subject to loss or failure or which cast shadows on the screen due to their disposition in planes perpendicular to the planes of the strips. Furthermore, my invention provides support for the strips over a major portion of their lengths rather than merely at a few selected points. My invention employs a plate in one surface of which are formed a plurality of grooves which are oriented so that one edge of each strip, or a major portion thereof, is accommodated by each groove. Thus, although the strips are fixed in place at only one end, one edge of each strip lies in a straight groove which keeps the strip from moving laterally across the face of the plate. If carefully anchored, even at only one point, the strip will not tend to rotate around the point of attachment.

For a better understanding of this invention, reference is made to the following drawings:

Fig. 1 is an elevational view toward the concave side of the translucent plate with the conductive strips in fixed position.

Fig. 2 is an elevational view from one end of the assembly shown in Fig. 1.

Fig. 3 shows schematically the location of the translucent plate and conductive strip assembly in a cathode ray tube, this diagrammatic representation of the plate showing it as lying in a plane instead of being concave as shown in Fig. 2.

Fig. 4 is a sectional view taken along line 4-4 of Fig. 1, showing metallic strips used in my invention.

Fig. 5 is a sectional view similar to Fig. 4, showing a modified means of supporting the metallic strips.

Fig. 6 is a sectional view of a portion of the plate illustrating the shape of that surface of the plate in which the grooves are formed.

Fig. 7 is a similar sectional view illustrating an alternative form of grooves.

Fig. 8 is a similar sectional view illustrating a plate in the surface of which rectangular grooves are formed in order to accommodate metallic strips.

The plate 10 is advantageously curved and composed of glass. ther be curved or composed of glass, it is important that it be rigid material and translucent to visible light. Translucent is here used in its broad sense to mean transmitting light either clearly or diffusely. A coating of phosphor 11 is applied to one surface of the plate 10, preferably the concave side. This phosphor coating 11 should be made thin enough to permit the passage of light therethrough. The purpose of this phosphor coating is to generate one of the primary colors when bombarded by electrons. This color is frequently red, but, as any of the primary colors may be substituted, it is appropriate to refer to the color produced generally as the first color.

Thin conductive strips 12a and 12b are arranged in front of the translucent plate 10 on the phosphor coated side thereof. These strips must be conductive in order to be capable of carrying a positive potential. The faces of each strip are close spaced to the faces of the adjacent strips and one edge of each strip is close spaced to and equidistant from theplate 10 throughout the length of said strip. The faces of each strip are coated with phosphors either of a second primary color or of a third primary color. Strips coated with the phosphor of a second primary color are designated 12a and those coated with a phosphor producing the third primary color are designated 12b. Strips 12a and 12b alternate so that a strip bearing a phosphor producing the second color will always be adjacent to strips bearing the phosphor producing the third color, and vice versa.

The location of an assembly similar to that of Figs. 1 and 2 in the color television tube is illustrated in Fig. 3. This tube is essentially a conventional cathode ray tube similar to kinescopes commonly used in black and white television art. Within the vacuum envelope 13 is an electron gun 14 which produces a stream of electrons. This electron beam is made to scan plate 10. Plate 10 is so located within the vacuum envelope 13 that its phosphor coated surface 11 may be conveniently scanned by the electron beam. The strips are always arranged so that the lengthwise elements of each strip are parallel to the lengthwise elements of every other strip.

The strips are also arranged so that scanned lines cross It has been found desirable to arrange the strips so that their faces lie approximately the strips at right angles.

parallel to the electron beam at all points. By so arranging the strips, the amount of blocking or interception of the beam by said strips will be minimized. Such interception of the beam is undesirable because it produces a dark line in the picture. Thus, in most instances,

it is expedient to arrange the strips radially so that the center from which they radiate is approximately coincident with the virtual center of deflection of the electron beam. With such an arrangement it is usually desirable to employ a plate which is a cylindrical segment whose axis passes through the virtual center of deflection approximately perpendicular to the plane of scanning. If this is done, conventional focusing and deflection means may be used. It is possible, however, to adjust the deflection and scanning of the electron beam in such a way that other arrangements of plates are possible. Thus, it is possible to arrange the strips parallel to each other along a planar plate along the curved surfaces shown in Figs. 1 and 2.

As the electron beam scans the phosphor coating 11 of plate 10, it must pass between successive adjacent pairs of strips 12a and 1212. When the strips both have the same voltage applied to them, so that a uniform field Patented Mar. 8, 1955,

While it is not essential that this member ei-- as shown in Fig. 3 as well as I is presented to the electron, it will not deviate from the straight line" path to the phosphor surface II. When, however, the positive bias on the adjacent strip 12a is increased, the negative electrons will be deflected from their -straight path {and tend to bombard the phos'phor cove'r'ed surface of this s'trip, 'thereby producing the second celdn On the other'ha'nd, when the positive bias on the strip 12b is increased, the electron beam will bedeflect'ed to this strip so that the third color will be produ'ce'd. The'second and third colors can be seen through the phosphor coating 11 because this coating is made thin enough to transmitlight. Alternate strips are connected together electrically so that the same potential-is applied to all strips bearing the same color phosphor. Thus successiv'e scanning's in red, blue and green are made by merely changing, the bias on the 'metallic strips and-re taining' one of the three bias combinations previously alluded to for'each of the separate scannings. The eye is capable of mixing these three primary color pictures togetlier so as to obtain a picture wherein all colors may be seen.

O'ne manner in which the strips are mounted is shown in Fig. 4. This manner is similar to that described in the aforementioned application Serial No. 249,356. However, in this instance, the translucent plate has parallel grooves in its surface. These grooves may extend the length of plate 10, or, as in the Fig. 4 illustration, a portion 10a may be left atboth ends of the plate into which the grooves do not extend. The grooves are not merely scratched on plate 10 but are advantageously of sufficient depth so that the thickness of the plate at such points 10b is materially decreased. The metallic strips 12a and 121) are fixed at only one end to U-shaped support members 16a and 16b respectively, which are mounted over opposite edges of the plate. The ungrooved portions 101: at the opposite ends of the plate afford a solid mounting for support members 16a and 16b throughout the full length of these members. On the other hand, the use of the ungrooved portion 10a makes it necessary to -cut away areas from portions of each strip which overlie the ungrooved portion 10a in order that the remainder of the edge in question may be accommodated within the grooved portion of the plate. Thus, as shown, rectangular areas may be cut away along the edges from opposite ends of the strips leaving steplike shoulders 19a and 19b. The strip 12b for instance, is cut so that the edge of the reduced width portion, beginning, at step 191), will overlie the ungrooved portion of the plate and contact support member 16!). Insulator 1711, which also lies atop the ungrooved portion 10:: of the plate adjacent supportmember 16b may be as thick as the support member. The increase in the width of the ship at step 19b will permit its edge to lie within the groove. At the opposite end of the strip, a similar step 19a accounts for a decrease in the width of the strip (12b so that its edge can ride atop insulator 17a. Strip 12b is not sufficiently long to contact support member 16a. Strip 12a is the same shape as strip 125, but it is arranged differently. The edge of one reduced width portion of strip 12a contacts and is affixed to support member 16a. The area cut out at its other end will overlie insulator 17b, but this portion of the strip is not long enough to contact support member 16b.

The structure thus described has advantages in those instances where a portion of the strip may be accurately cut away whereas the grooves in the plate cannot be accurately controlled in depth. Thus the depth of penetration into the groove may be kept uniform by basing the edge of each strip adjacent the portion cut away against insulators 17a and 17b respectively.

The strips are conveniently welded to the support members by the use of a high resistance wire member 18 which parallels the edge of the plate. To do this the electrodes of a resistance welder are placed one atop the strip and the other against the support member. As current passesthrough the support, the wire and the strip, the strip will be fixed in place due to melting and subsequent solidification of the wire 18. Since the strips 12:: and 12b will, in their final positioning, be flush against the surface of the support member 16a or 1611, they will have no opportunity to rotate about'the single point at which they are attached to their support.

An-alternative structureusing my invention is illustrated in Fig. 5. In this modification the grooves extend all the way acrossthe plate 10'. It is, therefore, rather inconvenient to use support members like those of Fig. 4. Accordingly, I employ support members 20a and 20b, which have a right angle cross section, at the opposite edges of the plate. These support members are advantageously composed of a metal which may be sealed to the glass of plate 10. One leg of each of these members extends well beyond the grooved face of plate 10'. The ends of the various strips are welded in place to the support members using wire members 18' as high resistancepoints, just as was done in the Fig. 4 construction. The use of a pair-of parallel wires to fix each strip to its support gives added strength to this connection. As in the previous case, alternate strips 12a are affixed to the support member at one end 20a and the remaining strips 1212 are aihxed to the support member 2012 at the opposite end. The strips are notsufficiently long to reach from one support to the other so that no shorting can occur between the supports.

In applying phosphor to the grooved face of plate 10, some phosphor may get into the grooves. While it is not harmful for some phosphor to penetrate the grooves in coating the surface of plate 10, it is often advisable to cover said grooves to prevent their filling up with phosphor. However, as long as the phosphor used isnonconductive, contact of the phosphor coating with a metallic strip, or the other phosphor thereon, will not prove detrimental.

Various shapes of grooves may be employed in the plate with the Fig. 4, the Fig. 5 or other possible support constructions. Three representative types of grooves are illustrated in Figs. 6, 7 and 8. The grooves of Fig. 6 and Fig. 7 lend themselves-to formation by various means well known to the art. For instance, a roller may be used to put groovesinthe glass while the glass is still soft. Also the glass may be cut by conventional glass cutting processes. The sawtooth type surface of Fig. 6 offers a particularly simple type of groove which may be readily fashioned in glass. Fig. 7 shows another relatively simple type of groove which has a flat bottom and a rounded surface between each groove.

Both the FigJG and Fig. 7 construction otter surfaces which present various angles to-the light which must be transmitted through the plate 10 and various thicknesses of the plate through which light must pass. These factors tend to produce diffusion of the light passing through the plate, so that points which would otherwisebe dark because of shadows cast by strips and 12b during scanning are eliminated.

Fig. 8 shows a structure wherein plate 10 has rectangular grooves formedin its surface. These rectangular grooves are precision formed to snugly accommodate strips 12a and 12b. If this fit is sufiiciently snug and the. grooves are precision formed in their correct relative positions, the strips 'may be accurately assembled merely by placing them in their grooves. To obtain grooves of this sort I employ'certain special types of glass which havea peculiar photo-sensitivity. This glass when exposed to ultra-violet light through a negative will'be so acted upon that subsequent etching will produce precision grooves of .a predetermined size. The grooves, thus formed, provide a means of easily and accurately mounting and aligning the various strips.

Grooves in many other shapes and forms may be employed with varying success when using my invention. Any arrangement ofparallel grooves of any shape formed in the translucent plate 10 so that they will accommodate the metallic strips 12a and 12b and hold them against sidewise movement is within the scope of my invention.

I claim:

A color-televisiontube comprising'an envelope having an electron gun in one end thereof and a plate of translucent material in the other end thereof, the electron gun being adapted to direct an electron beam toward said plate along a predetermined controlled path, said plate having a plurality of parallel grooves in the side thereof directed toward the electron gun, the surface of the plate between the; grooves being coated with a phosphor of a first color, a pluralityof thin concluctive strips arranged with their edges lying in respective grooves inthe plate, whereby said grooves preventlateral displaceme'ntof thefstrips and retain the strips in constant predetermined spaced relation, alternate strips'having aphos'phor of a second color thereon and the remaining strips having phosphor of a third color thereon, and means for retaining the strips in the grooves and simultaneously connecting the respective groups of strips having phosphor of one color thereon to respective voltage sources comprising a conductive member mounted on one edge of the plate and connected in conductive supporting relation to one end of each of the group of alternate strips having phosphor of the second color thereon, and a second conductive member mounted on the opposed edge of the plate and in conductive supporting relation to one end of each of the group of alternate strips having phosphor of the third color thereon, said conductive members each having a portion overlying the side of the plate opposite the face having the grooves therein and having a second portion extending in a plane substantially parallel with the path of the electron beam, the strips being secured to said second portions whereby the strips are prevented from moving in a direction normal to the surface of the plate and out of their respective grooves.

References Cited in the file of this patent UNITED STATES PATENTS 

